The invention relates generally to aligning a gun barrel in relation to a target. In particular, the invention relates to methods for determining and minimizing the miss distance between a gun barrel's line-of-fire and a optional sensor's line-of-sight.
The United States Navy operates combat vessels, some of which are equipped with shipboard artillery, including guns having a five-inch (5″) bore for its barrel. The Potomac River Test Range (PRTR) at Dahlgren, Va. is one of the Navy's premiere installations for developing and testing Gun Weapon Systems (GWS). Prior to firing tests of the 5″ gun for example, a gun alignment must be performed to match the aimed position with the location at which the projectile ultimately arrives. This necessitates aligning an electro-optic (EO) sensor and the gun pointing angle. If the EO/gun combination is not aligned, the gunner does not have an accurate gun pointing angle, constituting a prohibitively unsafe condition.
A typical gun alignment requires eight man-days (four people working two days of eight-hour shifts). A high accuracy Global Positioning System (GPS) receiver is disposed in the barrel of a test gun to establish the gun's position in relation to a world coordinate system for reference. Next, a target boat with a similar GPS receiver is dispatched onto the PRTR to establish the target's position in relation to the reference coordinates. The gunner for the test gun aims the barrel at the target boat using an EO sensor to point the barrel at the target boat. Measurements of where the gun actually points to versus where the gun expects to be aiming at are conducted. After several iterations, calculations of the errors in barrel/EO misalignment are performed. The resulting errors are applied to a calibration to minimize the barrel/EO misalignment.